simulation social graph

hi,
is there any technique by which can simulate social graph for an community?

I have dataset from online forum , it shows actions of users overtime.
But, I have not social graph for these data .
The authors did not provide social graph.
what I have to do in this case? what are the alternatives?

it seem to me I did not be clear.
what I mean, my work is detection of community.
to do that , I must have social graph.I got dataset, but have no social graph.
there are research groups publucate dataset with social graph for an community.

Some research groups publish dataset with social graph for an community.
unfortunately, the dataset that I got it did not attached with social graph.
Are there anyway to simulate social graph?